class Logger

A Logger is used to log messages about a particular component of an application.

Loggers are organized hierarchically according to name, descending from the root logger, "global." A period denotes levels in the hierarchy. For example, global is the parent of com is the parent of com.tibco is the parent of com.tibco.gi, etc.

A Logger has a level that determines what severity of messages will be handled. Messages with severity below the level of the Logger will be ignored. If the level of a Logger is not explicitly defined, the level is inherited from its parent.

A Logger can have any number of handlers, each of which can output a log message to a different place. By default a logger will also forward log messages to the handlers of its ancestors, although this can be disabled per Logger.

A typical usage pattern is to create a Logger for each class, setting it as a private static field of that class, as in the following code example:

jsx3.Class.defineClass('eg.Thing', null, null, function(Thing, Thing_prototype) {
  
  // import jsx3.util.Logger
  var Logger = jsx3.util.Logger;
  // create Logger for this class
  Thing._LOG = Logger.getLogger(Thing.jsxclass.getName());
  Thing.prototype.init = function(arg1, arg2, arg2) {
    Thing._LOG.debug("received args: " + arg1 + ", " + arg2 + ", " + arg3);
    if (isNaN(arg1)) {
      Thing._LOG.warn("arg1 is not a number, setting to 0");
      this._one = 0;
    } else {
      this._one = arg1;
    }
  };
});

If the creation of the log message is expensive (depending on the implementation, toString() can be expensive), isLoggable() can be used to check whether the log statement will actually be handled before creating the log message:

if (LOG.isLoggable(jsx3.util.Logger.INFO))
  LOG.info(anObject.toString());